The disclosure relates to a bearing element, to a sliding bearing having a bearing element of this kind configured to support a drive shaft of a hydraulic machine, and to a hydraulic machine having a sliding bearing of this kind.
Publication DE 103 00 070 A1 has disclosed a hydraulic machine in the form of an axial piston machine of swashplate construction. This machine has a drive shaft connected to a drive mechanism. Said drive shaft is supported in the radial and axial directions in a machine housing by two rolling contact bearings arranged in an X configuration. During the operation of the axial piston machine, the asymmetric driving forces from the drive mechanism acting on the drive shaft lead to deflection of the drive shaft. This leads to extremely nonuniform loading of the rolling contact bearings and, as a result, these exhibit relatively high wear, leading in turn to a relatively short service life and shorter maintenance intervals. Moreover, with rolling contact bearings of this kind there is essentially no possibility of compensating for an alignment error of the bearings, where said bearings are arranged offset relative to a longitudinal axis of the drive shaft, and this likewise leads to higher wear of the rolling contact bearings due to asymmetric loads.
Document DE 102 20 610 B4 discloses an axial piston machine having a drive shaft which, on the one hand, is provided with rolling support via a rolling contact bearing and, on the other hand, is provided with sliding support via a spherical bearing. The spherical bearing has an inner bearing sleeve, rigidly connected to the drive shaft and has an outer cylindrical surface as a sliding surface. The bearing sleeve slides in a cylindrical inner circumferential surface of an annular element arranged so as to prevent relative rotation, which has an outer circumferential surface of convex cross section. The annular element, in turn, is supported by its outer circumferential surface of convex configuration in a further outer annular element with an inner circumferential surface of concave configuration. The annular element is supported such that it is pivotable about a pivoting axis extending radially relative to the longitudinal axis of the drive shaft. The further annular element is fixed in a machine housing. A pin projecting from the outer circumferential surface of the inner annular element is provided to connect the pivotable inner annular element to the outer annular element so as to prevent relative rotation. Said pin projects into an elongate hole formed in the outer annular element. A longitudinal axis of the elongate hole extends in the direction of the longitudinal axis of the drive shaft. Deflection of the drive shaft is compensated for by virtue of the pivotable inner annular element of the spherical bearing. The disadvantage here is that the spherical bearing has extremely complex configuration in terms of device engineering and requires a large amount of installation space.
German Patent 923 631 discloses a shaft supported by two sliding bearings, wherein the sliding bearings allow for compensation of deflection of the shaft. In this case, one embodiment of a sliding bearing has a ring-shaped diaphragm-like bearing element. An annular groove is introduced into the inner annular surface of the bearing element, thereby forming two mutually spaced annular webs, which are securely connected to a sliding bush. The shaft is guided in a rotatable and axially movable manner in the latter. An outer surface of the diaphragm-like bearing element is convex in cross section and is guided in a sliding and pivotable manner in a correspondingly concave inner circumferential surface of a machine housing. Deflection of the shaft is compensated for, on the one hand, by deformation of the diaphragm-like bearing element and, on the other hand, by pivoting of the bearing element relative to the machine housing. The extreme complexity of the sliding bearing in terms of device engineering is likewise a disadvantage here. Another disadvantage is the fact that, in the event of deformation of the bearing element, power flows between the bearing element and the sliding bush via the annular webs, giving rise to high stresses in the region of the annular webs. These can disadvantageously lead to deformation of the annular webs and this, in turn, can result in release of the connection between the bearing element and the sliding bush. Moreover, the sliding bearings in this publication also require a large amount of installation space and are relatively difficult to assemble, due to the spherical outer circumference of the bearing elements.
Document DE 10 2007 018 794 A1 shows a sliding bearing for a shaft. In this case, an elastically deformable ring-shaped bearing element is provided. Said bearing element has an L-shaped cross section and has a wide outer cylindrical surface and a narrow inner cylindrical surface. The bearing element is rigidly connected to the shaft via the narrow inner cylindrical surface. The bearing element is arranged in a sliding manner in a bearing bush rigidly connected to a housing via the outer cylindrical surface which serves as a sliding surface. In this case, deflection of the shaft is compensated for by elastic deformation of the bearing element, although the deformation of the bearing element disadvantageously has the effect that the outer cylindrical surface, i.e. the sliding surface of the bearing element, is severely deformed, with the result that the sliding bearing is subject to comparatively high wear.
Faced with this situation, it is the underlying object of the disclosure to provide a bearing element, a sliding bearing and a hydraulic machine which are of simple and low-cost construction in terms of device engineering and have low wear.
This object is achieved by a bearing element, by a sliding bearing and by a hydraulic machine as described below.